It is common practice for electronic systems, such as computers or servers, to reject the heat produced by electronic components, such as the microprocessor, via air-cooled heat sinks. As the amount of this heat increases, this process is typically enhanced by employing extended surfaces on the heat sink, such as fins, and often the addition of a fan to force cooling air over the fins. However, as the amount of heat and the heat concentration increases, these practices can be insufficient for the required component heat flux or operating temperature. Also, as these higher power components continue to shrink in size, the number included in a given volume increases. Because of the increased density, the amount of heat rejected to the surrounding air can become too great for the air and/or the air-conditioning system to absorb. For example, many present electronic devices, such as computer servers, telecommunications switches, routers, etc., are manufactured in industry standard dimensions for installation in racks where as many as forty-two (42) units can be installed in a vertical stack. Each server may have two microprocessors, rejecting over 132 watts each, resulting in more than 11 kW of heat being released by just the microprocessors. This heat concentration far exceeds the ability of typical air cooling systems to absorb the heat.
Fluid circuits have been used in the prior art to channel the high heat release of xe2x80x9csupercomputersxe2x80x9d, but these systems have required special thermal conduction modules and intricate pumping, piping and cooling circuits within the computers. These internal cooling circuits also required special methods for servicing and replacing components and modules, preventing this technique from gaining wide acceptance and use. Additionally, there is also a reluctance to introduce a large amount of conductive fluid, such as water, into the computer because of potential electric safety issues.
The present invention overcomes the problems recited above and the deficiencies of the prior art by providing a thermal path for the generated heat that has a higher cooling capacity than simple air cooling but that does not require the manufacturer of the electronic or computer equipment to physically connect the ultimate heat absorbing fluid to each electronic device. Therefore, there is no need to introduce cooling fluid into the electronic enclosure, solving many of the problems with fluid cooling identified above.
Not all heat producing components in the electronic system may require cooling directly through this thermal path, and may continue to release their heat to air. One embodiment of the present invention adds extended surfaces to the final heat exchanger to absorb this heat. Furthermore, the importance of these electronic systems may be such that continuous operation is essential, as they may be sued for sales, communication, or other critical operational functions that must always be on-line. Therefore, a second, redundant cooling circuit may be provided to ensure continuous operation in the event of a failure of either cooling circuit.
The present invention solves the above-identified problems of the prior art in its various embodiments.
In one embodiment, the present invention comprises a cold plate, pump, intermediate heat exchanger, final heat absorber, and a small amount of thermal fluid. The cold plate is thermally connected to the heat generating electronic component. The pump circulates the thermal fluid employed to absorb the heat. The intermediate heat exchanger then transfers the heat to the final heat absorber.
The circuit comprising the cold plate, pump and intermediate heat exchanger is a sealed system. The cold plate and the intermediate heat exchanger may include thermal enhancing techniques such as unique flow channels or internally extended surfaces to improve their ability to absorb or transmit the heat. Thermal tapes or other materials may be employed to reduce the thermal resistances in the circuit. The fluid may be water, a dielectric fluid, a refrigerant, or other suitable thermal chemical. The final heat absorber may also include thermal enhancing techniques to improve its thermal performance. The thermal fluid employed in the final heat exchanger may also be water, a dielectric fluid, a refrigerant, or other suitable thermal chemical.
In an alternative embodiment, the present invention comprises a heat pipe, intermediate heat exchanger, final heat absorber, and a small amount of thermal fluid. The heat pipe consists of an evaporator, condenser, and interconnecting tube. The evaporator is thermally connected to the heat generating electronic component. The thermal fluid transmits the heat from the evaporator to the condenser through the tube via the mechanisms of vapor pressure and/or wicking. The condenser is thermally connected to the intermediate heat exchanger, which then transfers the heat to the final heat absorber.
The heat pipe is a sealed system. The evaporator, condenser, and intermediate heat exchanger may include thermal enhancing techniques such as unique flow channels or internally extended surfaces to improve their ability to absorb or transmit the heat. Thermal tapes or other materials may be employed to reduce the thermal resistances in the circuit. The fluid may be water, a dielectric fluid, a refrigerant, or other suitable thermal chemical. The final heat absorber may also include thermal enhancing techniques to improve its thermal performance. The thermal fluid employed in the final heat exchanger may also be water, a dielectric fluid, a refrigerant, or other suitable thermal chemical.